Vaillant has a stainless steel heat exchanger Worcester is aluminium- in my experience NO contest go for Stainless every time better condensing cycle

Valliant everytime,can't even switch the worcester off on the boiler,you have no control of the hot water temp,if you are an accredited installer a 3,4,5 year warranty can be added at a small cost

Worcester definitely, if you can afford it go for the 30si, then you can have temperature control on the hot water, the only complaint i ever get from customers regarding worcester 28i jr is the hot water is too hot because you cant control the hot water temp. The aftercare with worcester is brilliant, if anythink goes wrong with it they are out the next day.

Regards

Matt

worcester every time the heat exchanger is guaranteed for 10 years and the heat transfer on the heat exchanger is the best i know the arguments about stainless steel and all that and i used to fit viessmanns all the time but wait till they go wrong and they dont really want to know get worcester fitted and you may get a 7yr warrenty if you get the right fitter.
regards
am heating

Both are has good as each other, both will do the job required.

Bill
Pipe DReams Plumbing Services

Both would be suitable from what you have described,I would go for the worcester i have the vaillant in my house just over 2yrs and its broke 3 times.
It would be best to advertise locally and get quotes if you are anywere near me give me a call.

I think vaillant and Worcester are very similar and that's all we fit either those two, have a look at a boiler called viessman give you 5 year warranty, about £200 cheaper than those two boilers you get a longer guarantee, the viessman most engineers don't fit but only the other day I see one fitted and there very quiet. Good luck with your boiler, any questions contact me no problem